This invention relates generally to semiconductor fabrication techniques and, more particularly, to a technique for regrowth of certain semiconductor materials over a structure that includes a dielectric material. Dielectrics are used in many applications of semiconductors, to maintain electrical separation between conducting and metallic regions of semiconductor structures. When the semiconductor materials are silicon based, there is little difficulty in growing such materials over structures that include dielectrics. Polycrystalline silicon is inherently conducting and forms a desirably low-resistance contact with other regions of a semiconductor structure.
Unfortunately, the same advantages are not inherent to the class of semiconductor materials generally referred to as Group III–V materials, i.e., those semiconductor materials falling into Groups III and V of the periodic table of elements. These materials, such as indium phosphide (InP) and gallium arsenide (GaAs), are the semiconductors of choice for high-speed electronic and optoelectronic applications. Group III–V semiconductors grown over dielectrics are, for the most part, inherently non-conducting. In those regions where a regrown layer overlaps a semiconductor region, the electrical properties result in an undesirably high resistance between the underlying semiconductor region and the regrown layer. Regrown group III–V semiconductor materials also typically have an undesirable morphology. Specifically, some classes of regrown Group III–V semiconductors present a surface that is so rough as to inhibit processing, although, in general, they are relatively good conductors. Other classes of Group III–V semiconductors are smoother, rendering them easier to process, but these are generally less conducting.
Accordingly, there is a need in the semiconductor fabrication art for a technique that facilitates the regrowth of Group III–V semiconductor materials over a structure that includes dielectrics, and that provides good electrical contact with underlying semiconductor regions. The present invention meets this need.